Track tamping machine



Feb. 10, 1959 F. PLAssER ETAL 2,872,878

TRACK TAMPING MACHINE v Filed Dec. 18, 1956 2 Sheets-Sheet 1 Ela-: 1

NVENTOR` Franz PLHSSEE Lne? 'IEUREQ I Feb. 10, 1959 F, PLASSER ETAL I 2,872,878

TRACK TAMPING MACHINE Filed Dec. 1`8, 195e 2 sheets-sheet 2 INVENTOR. HHM/z PZAsss .WMF Wiz/,ffl

United States Patent O TRACK TAMllING MACHINE Franz Plasser and Josef Theurer, Vienna, Austria Application December 18, 1956, Serial N o. 629,183 Claims priority, application Austria December 23, 1955 3 Claims. (Cl. 11M-12) The present invention relates to ballast tamping machines comprising preferably vibratory pairs of tamping tools arranged to tamp the ballast underneath railroad ties between pairs of tools which are pressed together. More particularly, it concerns a mechanism for adjusting the opening width of tamping tool pairs.

Highly eilcient and largely automatic machines of this type have been developed in recent years, one such machine, with various modiiications being described and claimed in our U. S. patent application Serial No. 462,086, tiled October 13, 1954. Generally speaking, such track tamping machines comprise pairs of cooperating tamping tools mounted on a vertically movable carrier and means for varying the distance between the tamping tools of each pair.` The ballast is packed under a tie by placing the lower ends of the tamping tools of each pair into the ballastrat each side of the tie and forcing the tamping tools together while preferably vibrating them simultaneously.

While the invention will be described and illustrated in connection with a machine as disclosed in our abovementioned prior application, it will be obviousl that it is in no way limited to this specic track tamping machine.

Itis the principal object of this invention to construct a ballast tamping machine with cooperating pairs of tamping tools so that the machine may be operated continuously and without time-consuming interruptions to tamp successive ties of dilerent width, for instance double ties positioned under rail joints.

vIt is another object of the invention to control the maximal pressure exerted upon the closing tamping tools automatically when their opening distance is adjusted to accommodate ties of different width.

ln accordance with the invention, we provide adjustable limit stop means for controlling the opening width of the tamping tool pairs according to the width of the tie to be tamped.

As applied to a track tamping machine wherein the tamping tools are linked with elements which may be moved longitudinally in the direction of the track to vary the distance between the two tools of each pair, the invention provides adjustable limit stops which are engageable directly by said elements and which delimit the outward movement of said elements and, accordingly, the opening width of the tamping tools.

According to one preferred feature, the invention is applied to the machine disclosed in our prior application Serial No. 462,086, wherein each tamping tool is linked with a cylinder which is slidably mounted on a fixed piston rod carried by the tamping tool carrier. A piston is arranged on the piston rod in each cylinder and, by applying a pressure fluid to one or the other cylinder chamber, the cylinder is moved on the rod and thereby moves the tamping tool linked with it. The limit stop means include a fixed stop mounted on the piston rod to limit the farthest outward movement of each cylinder and its associated tamping tool, thereby establishing the widest opening width of the cooperating tamping tools, and movable stops arranged to be moved into and out of engagement with the piston rod between each cylinder and its associated iixed stop, establishing a narrowed opening width when the movable stops engage the piston rod.

In accordance with another preferred feature of this invention, the adjustment of the movable stops controls not only the opening width of the tamping tools but automatically changes the maximal pressure which may be exerted by the tamping tools during their closing (tamping) movement.

The above and other objects, features and advantages of the present invention will be more fully explained in the following detailed description of a now preferred embodiment thereof, taken in conjunction with the accompanying drawing which illustrates certain structural details without in any way limiting the invention thereto. In the drawing,

Fig. 1 is a schematic side view of a mobile track tamping machine, showing the tamping tool opening and closing means in section;

Fig. 2 illustratesv the arrangement according to the invention for controlling the mechanism which limits the opening width of the tamping tools; and

Fig. 3 is the perspective view of the tamping tool carrier with the mechanism of the invention shown in conjunction with a single tamping tool, for claritys sake, identical movable stop means being provided for each tool.

Referring to Fig. l, there is shown a mobile truck mounting the frame 1 and two support columns on which th'elvertically adjustable tamping tool carrier 2 is glidablysupported. The upper ends of each cooperating pair of tamping tools 3 are linked to mounting arms 4 which are vibrated by cam shaft 5. The means for varying the distance between the tools of each pair comprise pistons 6 mounted on piston rods 7 which are tixedly journaled in the tamping tool carrier, the pistons gliding in closed cylinders 8 which are movably mounted on the piston rods. The tamping tools 3 are substantially centrally linked at 9 with the movable cylinders. The central block 10 serves to removably retain the piston rods 7 in coaxial position.

Pressure fluid conduits 11 and 11 are arranged to sup-y ply pressure uid to cylinder chambers S and 8", respectively. When pressure uid, i. e. oil, is supplied through the central conduit 11, the built-up pressure in chambers 8" willforce cylinders 8 and associated tamping tools 3'to move inwardly, i. e. the tamping tools will be closed into tamping action. When it is desired to open the tools after tamping, pressure fluid, for instance compressed air, may be supplied to chambers 8' through conduits 11.

Fixed limit stops 12 are mounted at the outer ends of the piston rods to limit the outermost position of cylinders 8 and thus to determine the largest opening width of the tamping tools. Movable stops 13 are mounted on the tamping tool carrier for movement adjacent the xed limit stops, the movable stops being positonable on the piston rods between cylinders 8 and limit stops 12. When the movable stops are thus positioned and the cylinders are pressed outwardly, the xed limit stops 12 will support the movable stops against the lateral pressure exerted upon them by the cylinders.

The movable stops have the width s. Therefore, when they are removed from the piston rods 7, the outward path of each cylinder S is increased by the distance s and the opening width of the tamping tools is increased by 2s. The position of fixed limit stops 12 is chosen so that the distance of the fully opened tamping tools 3 is suiicient to tamp double ties 40 when cylinders 8 contact the limit stops. The width of movable stops 13 is such that, when they are in position on the piston rods, they will limit the outward movement of the tamping tools to an opening width suilicient for tamping the normal ties 39.

As will appear from Fig. 2, each movable stop- 13 comprises bell crank lever 14, pivotable about axle 16 which is journaled in the tamping tool carrier 2. ArmY 1e carries the semi-circular stop portion 13 which is adapted to engage piston rod 7 when the bell crank lever is pivoted into position I to limit the path of cylinder 8 on rod 7. To eiect the pivoting movement of the bell crank lever, its arm 15 is linked to rod 17 which is actuatable by movement of piston 18 in cylinder 19. The stop 13 is held in engaging position I (full lines in Fig.

2) by the pressure of spring 2l) forcing piston 18 to they left, as seen in the drawing. When it is desired to disengage the stop from the piston rod 7, pressure iluid is supplied to the cylinder 19 through conduits 21, Z2,v

which may be exerted by the tamping tools when theyare closed. This maximal pressure is reached either when the ballast compacted between the tools is so dense that it will resist any further pressure by the tools or when the tools contact stops (not shown) provided to limitI their inward movement (similar to outward-movement stops 12 or 13).

Relief pressure valve 24 comprises spring 27 which is biased to determine the maximal pressure, one end of the spring pressing against the valve closure element, i. e. ball 25, while its other end presses against a piston rodAV carrying piston 26 glidably mounted in cylinder 31. The position of the piston will determine the pressure exerted by spring 27 on valve closure element 25. The chamberof cylinder 31, whose volume increases when pressure iluid is supplied to the cylinder, is in communication with the atmosphere through bore 31 to permit air to escape from the chamber. The valve also includes an adjustment screw 28 which permits control of the bias of spring 27 and thus of the pressure to which the valve will respond when piston 26 is not under the inuence of pressure fluid supplied through conduit 23, i.- e. when ties 39 of normal width are tamped.

The path of piston 26 in cylinder 31 is limited by stop 32 so that, even when the cylinder chamber is filled to capacity with pressure tluid, the pressure exerted on valve spring 27 cannot exceed a predetermined magnitude.

To obtain the desired pressure control of the arrangement according to this feature of the invention, cylinder 19, which serves to move stops 13, and cylinder 31, which determines the action of relief pressure valve 24, are supplied by the same pressure fluid conduit 22. The supply of pressure fluid to these cylinders is so controlled that it eiects not `only the movement of stops 13 to position 1I to allow wider opening of the tamping tools but simultaneously increases the pressure of spring 27 in valve 24, thus increasing the maximal pressure which may be exerted by the closing movement of the tools. The valve is connected in the uid pressure conduit 11 through branch conduit and, when excess pressure occurs, fluid will be conducted from conduit 11 through branch conduit 3h and outlet conduit 29 into a storage container (not shown),

The control of pressure uid supply to conduit 22, and thus to cylinders 19 and 31, is effected by a threeway stopcock including control element 33 and control lever 34. The control element has bores 35 and` 3,6for selective connection of conduit 22 vwith inlet pipe 3 8- and outlet pipe 37. In position II (broken lines of Fig. 2 when the stops 13 are disengaged), bore 3S connects conduit 22 with inlet pipe 33 which is connected to a supply of pressure luid (not shown). The pressure fluid will be conducted through conduit 21 into cylinder 19 to press piston 18 to the left and pivot stop 13 olf piston rod 7. Simultaneously, pressure fluid will enter cylinder 31 through conduit 23 to press down piston 26 and increase the bias of spring 27. In position I, on the other hand, bore 36 connects conduit 22 with outlet pipe 37. Springs 20 and 27 will move pistons 18 and 26, respectively, back into position l and the displaced pressure uid will ilow back through conduits 21, 23 and 22 into outlet pipe 37 wherefrom it will be led into a storage tank (not shown).

This pressure control arrangement is of great importance and considerable practical value because the tamping tools must obviously exert greater tamping pressure when they are used to tamp the larger amounts of ballast under double ties dit. Thus, effective operation is possible only if the maximal pressure of the tamping tools can be increased when wider ties are tamped.

` With the automatic controls provided by this invention,

the adjustment of the pressure and its correct size is no longer leftfto ythe judgment of the machine operator. Rather, the maximal pressure which may be exerted by the closing tamping tools is automatically adjusted when the opening width is adjusted. This change of the opening width must be effected by the operator in any event and it involves no loss of time, being effected merely by pushing lever 34. This will automatically control the pressure which may be exerted by the closing tamping tools.

Obviously, this pressure control arrangement may be incorporated in any track tamping machine which comprises means for limiting the maximal closing pressure of the tamping tools, for instance a friction coupling arranged in the mechanism for moving the tamping tools. It is particularly advantageous in the hydraulicallyoperated machine described hereinabove.

The machine operates as follows:

Assume that the machine has just completed tamping of a tie 39 of normal width and the truck with raised tamping tool carrier 2 is moved into tamping position for double tie 40 which requires a larger opening width of tamping tools 3. The operator now pushes lever 34 from position I to position II so that pressure fluid from a storage tank (not shown) is supplied through conduits 38, 35 22, 21 and 23 to cylinders 19 and 31, respectively. Piston 13 will move to the right (as seen in the drawing) against the pressure of spring 20, pushing link 17 and pivoting bell crank lever 14, 15 about axle 16 to lift stop 13 off piston rod 7 into position 11 (broken lines). This will open` the path for cylinder 8 to move outwardly against ixed limit stop 12 so that the path of movement of the cylinder is increased by s.

Simultaneously, the pressure fluid supplied to cylinder 31 will move piston 26 downwardly until it contacts stop 32. The piston will increase the bias of valve spring 27 so that the spring will exert increased pressure on valve closure element 25 which closes off relief pressure conduit 29 from the conduit 11 which communicates therewith through branch pipe 30. This will allow increased pressure in the conduit 11 which supplies cylinder chambers 8 and thus closes the tamping tools. Thus, the maximal closing pressure of the tamping tools is automatically increased when their opening width is increased.

The operator now opens the tamping tools by supplying pressure fluid to outer lchambers 8 of the cylinders 8 through pipes 11 until the cylinders contact fixed limit stops 12. He then lowers the tamping tool carrier with the opened tamping tools until the lower ends of the tools are submerged in ballast 41 at each side of double tie 40 He now` supplies pressure iluid to chambers 8" tomove the tamping tools toward each other and to tampthe ballast while the tamping tools-are simultaneously vibrated in a manner well known.

The closing movement of cylinders 8 will continue until either the ballast 41 is so dense that it will resist any further movement of the tamping tools or until the cylinders contact inward stops (not shown) which may be adjustable. As soon as resistance to further movement is encountered, relief pressure valve 24 goes into action, ball 25 being lifted under the pressure from fluid entering from conduit 11 through branch pipe 30 and being discharged through pipe 29. This will occur in position Il at a higher pressure in conduit 11 than in position I because spring 27 is under increased bias by piston 26 in position II. Fluid discharged through pipe 29 will be led back to the fluid storage tank.

As soon `as the operator recognizes that the tamping operation is finished, i. e. that the tamping tools move no further, the tamping tool carrier is raised again. If the next tie is narrower again, i. e. of normal width, lever 34 is moved into position I so that conduit 22 is connected to discharge pipe 37. Under the pressure of springs 20 and 27, pistons 18 and 26 will displace the pressure iiuid in cylinders 19 and 31 until they have reached position I. The displaced uid will ow back into the storage tank through discharge pipe 37 and stop 13 will engage piston rod 7 to limit the opening movement of the tamping tools. Thus, the opening Width `of tamping tools 3 is decreased by 2s. Simultaneously, the pressure exerted by piston 26 on spring 27 is decreased and the relief pressure valve 24 will respond to lower maximal pressure in conduit 11. This closing pressure, as needed for tamping narrower ties, may be further adjusted by adjustment screw 28. This operation may be repeated continuously for tamping successive ties of differing or equal width.

While the invention has been described in connection with a now preferred embodiment, it will be understood that many modifications and variations may occur to the skilled in the art, particularly after beneiiting from the present teaching, without departing from the spirit and scope of this invention as defined in the appended claims.

What we claim is:

1. In a track tamping machine which comprises pairs of tamping tools carried by a vertically adjustable carrier and linked to respective elements which may be moved in the direction of the track to vary the mutual distance of the tools of each pair, whereby the tools may be moved from an open position into a closed position to tamp ballast therebetween -and under a tie positioned between the tools: adjustable stop means larranged to move from inoperative position permitting a greater width of opening between the tamping tools into an operative position adjacent each movable element to limit the outward movement of the tamping tools according to the width of the tie to be tamped, mechanical means for the selective adjustment of the adjustable stop means, means for controlling the maximal pressure applied against the tamping tool moving elements in said closed position, and means operatively connecting the mechanical means and the pressure control means for adjusting the maximal pressure control means in response to the adjustment of the stop means, the maximal pressure upon said tamping tool moving elements being increased when the stop means is in the inoperative position.

2. In a track tamping machine which comprises pairs of tamping tools carried by 'a vertically adjustable carrier, fluid pressure means for varying the mutual distance of the tools of each pair, whereby the tools may =be moved from an open position into a closed position to tamp ballast there-between and under a tie positioned between the tools, and pressure relief valve means arranged in said fluid pressure means and operable to control a maximal pressure of the tamping tools in said closed position: adjustable stop means arranged selectively to move from an inoperative position permitting a greater width of opening between the tamping tools into an operative position limiting the outward movement of the tamping tools according to the width of the tie to be tamped, and means connected to and operated by the adjustable stop means for operating the pressure relief valve means, adjustment ot' the stop means into an inoperative position which allows widest opening of the tamping tools increasing the pressure-resisting force of the valve means.

3. The track tamping machine of claim 2, comprising means for pivoting the adjustable stop means into and out of the inoperative position, said pivoting means including a cylinder, a piston glidably mounted in said cylinder and defining two chambers therein, means for supplying pressure fluid to one of said chambers, a compression spring mounted in the other one of said chambers and biased to press against the piston, and connecting means linking the glidable piston to the pivotal stop means; means for supplying pressure iluid to said valve; and common pressure fluid charging means for said two pressure iluid supply means whereby pressure will be exerted simultaneously against the pistons in said cylinlder and the valve upon operation of the uid charging means.

References Cited in the le of this patent UNITED STATES PATENTS 1,367,452 Bolton Feb. 1, 1921 1,965,057 Rittenhouse July 3, 1934 2,052,943 Scheuchzer Sept. 1, 1936 2,057,087 De Millar Oct. 13, 1936 2,475,723 Sanford July 12, 1949 2,712,287 Zurmuhle July 5, 1955 FOREIGN PATENTS 182,113 Austria May 25, 1955 

